Numerical Simulation-Based Structural Performance of Containment Structures Under Increased Pressurization and Depressurization Rates

The main functions of containment structures are equipment support and internal and external protection. As the final safety barrier of a nuclear power plant， the containment structure must meet high reliability requirements， and its structural integrity must be maintained throughout the life cycle of the plant. In order to verify the structural performance of the containment， a CTT test is required， which is characterized by high risk and long duration. Considering the practical needs of nuclear power plants， it is expected that the efficiency of safety assessment can be further improved by enhancing the pressurization and depressurization rates of the containment during the CTT test. Using the ANSYS finite element software， a numerical simulation was conducted with the M310 containment as the research object. Two sets of numerical models were established to compare the expected pressurization rate （pressurization at 80 kPa/h and depressurization at 40 kPa/h） and the actual pressurization rate of the M310 containment （pressurization at 40 kPa/h and depressurization at 14 kPa/h）， to investigate the effects of rate inchease on the structural performance of the containment. The results showed that after increasing the pressurization and depressurization rates， there was no significant difference in the pressure and gas velocity distribution inside the containment shell； the gas temperature exhibited similar trends during both heating and cooling， with a relatively small temperature difference between the two processes； there were no significant changes in concrete temperature or structural deformation. The simulation analysis verified that the structural performance of the containment shell remained within the safe range under the increased rate and met the operational requirements.